Here is a brief description of a significant new opportunity
for the development of affordable
large-area, flat-panel displays for consumer applications. On
this page you will find the abstract and a block diagram from a
patent application that I filed with the US Office of Patents and
Trademarks on September 5, 2000. It issued on March 18, 2003 and
can be viewed here.
If you find it interesting but are not actively developing
large-area displays, please notify others who may be interested
in such an opportunity. In any case, please contact me with your
questions or comments.

A low-cost, large-area display system having a backlight in
segments each positioned to illuminate a subfield of M rows of a
fast supertwisted-nematic (STN) display of N rows. Fields of Q+1
subfields are addressed by the method known as Active
Addressing using orthogonal waveforms of period MT/N where T
is the frame time. A subfield is addressed for Q+1 periods MT/N
of the row waveforms and illuminated during the last one. Fast
STNs allow Q to be small leading to a small effective multiplex
ratio with improved contrast and horizontal viewing-angle range.
A few additional leading and trailing rows may be addressed to
overcome vertical parallax. The row drivers are periodically
connected by switches that simply ground un-addressed rows. With
Q+1 also a divisor of N, subfield contributions to the column
waveforms can be calculated once and used Q+1 times in each
frame. For example, N=240, M=16, L=4 and Q=2 provide an effective
multiplex ratio of 57 and allow at least 2.2 msec for pixels to
turn on when the frame rate 1/T is 60 Hz. The viewing-angle range
can also be expanded by moving subfields a few rows in the scan
direction and advancing the integration time to equalize the
brightness of pixels illuminated by the next segment. For
example, if the turn-off time is 0.76T and the integration time
is shortened to 0.33MT/N, equalization is possible with turn-on
times as large as 3/4 of the turn-off time without decreasing
pixel transmittance by more than 50%. Dual-scan configurations
using N=240, for example, can display VGA or 480p formats.